How to assign specify driver to 2 devices

Hello.
Sorry for my question that is probably stupid (I'm not very familiar with drivers in linux)
but I can't find an answer to my problem:
I have a CentOS 5 system that I access trough SSH
I have 2 PCI devices that should use 2 differend "drivers" but one of this claim both the devices
and the automatic module loader assign it to both.
Unfortunately each device requires it's own driver to work properly.
How can I force the correct driver to be assigned to the device?
Thank you
And again sorry if this question has already been answered.